BIFT Generation

The BIFT contains entries used by a BFR in a BIERv6 sub-domain to forward multicast packets. The bit index routing table (BIRT) is the prerequisite for generating the BIFT. Figure 1 shows the process of generating a BIRT and a BIFT.

Figure 1 BIRT and BIFT generation process

The detailed process of generating a BIRT and a BIFT is as follows:

1. Each BFR in a BIERv6 sub-domain uses TLVs defined in IS-ISv6 for BIERv6 to advertise information about the local BFR-prefix, sub-domain ID, BFR-ID, BSL, and path calculation algorithm to other BFRs.
2. Each BFR obtains the BFR-neighbor to each BFER through path calculation and generates BIRT entries.
3. Each BFR performs a bitwise OR operation between the BFR-IDs in the BIRT entries with the same BFR-neighbor to obtain the F-BM and generates BIFT entries based on the BIRT entries.